Forssell SMP-2 and AEA TRP preamp comparison

[Fran Guidry]

The differences are small but in the range now considered audible by folks I have read:

TRP
Peak Amplitude: -1.27 dB
Minimum RMS Power: -75.79 dB
Maximum RMS Power: -10.68 dB
Average RMS Power: -23.11 dB
Total RMS Power: -20.64 dB

SMP-2
Peak Amplitude: -1.53 dB
Minimum RMS Power: -75.6 dB
Maximum RMS Power: -11.31 dB
Average RMS Power: -22.84 dB
Total RMS Power: -20.44 dB

The TRP has a peak at -1.27db, the SMP-2 is .26 db lower. But the average RMS power shows a difference of .27db in the other direction.

Once my buddy pointed out the difference and suggested just listening to the first few notes, I could reliably identify the two files. It took a lot of concentration, but I managed 5 straight correct selections before I gave up.

Naturally at these levels of difference the impression is not that one is louder or quieter, but that one is more veiled and the other more "clear."

I guess when I feel like torturing myself again I should adjust the gains to give the TRP a slight advantage and see if the tables turn. Listening with real care turns out to be a lot more work than I expected.

Fran

[BrianHanke]

Interesting to see the numbers at work here. I also had some success just listening to the first few notes. I was able to reliably pick which preamp was which in an ABX setting. Indeed, one sounds a little (and I do mean a little!) "flat" compared to the other.

[MichaelPatrick]

Thanks much for the numbers Fran. Those levels do present a difference one can hear but what it means vis a vis the qualities I heard is uncertain. I also wouldn't know if it's a difference in the mics as you suggest.

You raised all valid points. If I were doing the test and had time to spare, I'd probably swap the mics around and provide 4 clips.

[bove]

Originally Posted by MichaelPatrick

If I were doing the test and had time to spare, I'd probably swap the mics around and provide 4 clips.

This would be great! I had intended to switch the cables for a take with the mics swapped, but as usual, there were bigger issues to take care of that day and I didn't have the opportunity to do it. Perhaps I'll record a few clips again sometime.

Originally Posted by ISedlacek

mono

I frequently use R84s as mono spots in a multi-microphone setup, so that's why I was doing these comparisons in mono.

Originally Posted by Fran Guidry

I guess when I feel like torturing myself again I should adjust the gains to give the TRP a slight advantage and see if the tables turn. Listening with real care turns out to be a lot more work than I expected.

Fran, thanks for the info, I hope you've enjoyed listening! This is definitely an interesting ear training exercise. I noticed the inverse relationship between the peak level and RMS level of the two files while preparing them for listening, and I tried to split the difference while adjusting the overall levels.

Originally Posted by MichaelPatrick

The important reflections, as I see it, would come from behind the trumpet player, blocked by his body. That factor could, I think, make a difference just as you say - especially if the room is small and the wall is reflective.

The wall behind the trumpet player was about 8 feet away, is partially covered in decorative fabric, and is not very reflective.

[MichaelPatrick]

For fun, and with Bove's permission, I processed his horn clip (SMP-2).

I used a Bricasti M7 with large/near hall settings, slightly tweaked.

Clip 1: Horn with M7 only.
Clip 2: Horn with M7 lightly mastered.

P.S. They are MP3s because converting it to stereo increased the WAV size too much to upload.

[Audiop]

Originally Posted by BrianHanke

Interesting to see the numbers at work here. I also had some success just listening to the first few notes. I was able to reliably pick which preamp was which in an ABX setting. Indeed, one sounds a little (and I do mean a little!) "flat" compared to the other.

Did you really "pick a preamp" or did you pick a chain of components including different microphones at different positions? ;-)


/Peter

[jdtrbn]

As off-topic that's some pretty sounding playing.

[ABBA]

AudioP:

Did you really "pick a preamp" or did you pick a chain of components including different microphones at different positions? ;-)

My thoughts exactly.
Are these ribbons really so precisely matched?
So far I've only encountered mics from Earthworks, DPA and Schoeps
that gave no audible differences when compared to eachother.
LDCs and ribbons of the same make and model sound very different
in general IMO.

Perhaps in this particular test it would be a better idea to use a splitter and just one mic.

I appreciate the effort though.
Thanks.

ABBA

[bcgood]

Originally Posted by MichaelPatrick

For fun, and with Bove's permission, I processed his horn clip (SMP-2).

I used a Bricasti M7 with large/near hall settings, slightly tweaked.

Clip 1: Horn with M7 only.
Clip 2: Horn with M7 lightly mastered.

P.S. They are MP3s because converting it to stereo increased the WAV size too much to upload.

Sounds cool Michael, I like it.

-------------------------------------------------------------------------

Here's my entry, this time with the AEA TRP just to add a little fun.

TRP_TrumpetWithSPACE_bcgood.wav

[BrianHanke]

Yes, of course you're right. What I meant was that I could reliably tell the two WAV files apart.

Originally Posted by Audiop

Did you really "pick a preamp" or did you pick a chain of components including different microphones at different positions? ;-)


/Peter

[Audiop]

I like the way that sounds much more!


/Peter

[bove]

Thanks for posting those samples guys! It's fun to listen to different versions.

[bcgood]

Originally Posted by bove

Thanks for posting those samples guys! It's fun to listen to different versions.

You're welcome and thank you for the cool trumpet playing and recording examples.

[gutr2]

Nice one - thanks!
I could not hear any measurable differences between the two clips through my Dynaudio speakers, but when I put my Senn HD600's on, it was obvious and sort of familiar since I'm a proud owner of an SMP-2. Just nicer, bigger, smoother, etc..
Thanks again for the samples!

[bcgood]

Originally Posted by gutr2

Nice one - thanks!
I could not hear any measurable differences between the two clips through my Dynaudio speakers, but when I put my Senn HD600's on, it was obvious and sort of familiar since I'm a proud owner of an SMP-2. Just nicer, bigger, smoother, etc..
Thanks again for the samples!

If you get a chance check out my AEA TRP Space wave sample on your headphones. I put a new file up today.

I'm thinking of getting a pair of the Senn HD600's. How have you liked yours so far?

[gutr2]

Hey there,

Amazing "space" I love it!
Is that the Briscati too?

About the HD600's, people say they really need a good amp to sound their best, so I haven't experienced that yet. Nevertheless they are very revealing, very natural. In comparison, my other headphones sound pretty cheap, boomy bass, hyped "fake" highs, harsh mids, etc.

They are extremely comfortable and a joy to listen to music on for pleasure. I only wish they had more bass, but this could be improved with a better amp perhaps. The bass is there, nice and tight, but mixing with them I always end up with too much bass.

A

Originally Posted by bcgood

If you get a chance check out my AEA TRP Space wave sample on your headphones. I put a new file up today.

I'm thinking of getting a pair of the Senn HD600's. How have you liked yours so far?

[Audiop]

Yes HD600 is thin in the low bass. HD650 is better but to thick in the upper bass/lower mid. Overall I feel HD600 is the better mix-tool though.

Any decent amp will do and do not really change the bass.

Best IME is to use HD650 with a slight EQ to tame the 60Hz-350hz bump or so. I'm planning to build a two channel head-amp with built in notch for HD650 and bass gain for HD600.

Most people agree on these listening impressions and my measurements supports this as well.

Check graphs in post #12.

Nearfield monitor most similar to HD-650s?


/Peter

[bcgood]

Originally Posted by gutr2

Hey there,

Amazing "space" I love it!
Is that the Briscati too?

A

Thanks I had fun with sculpting this audio clip. No, it isn't the Britcasti. Basically I combined some of the reverbs that come in Pro Tools 8 with a smidgen of Lexicon reverb.

Thanks for the HD 600 review, I think I'll probably pick up a pair if nothing else just to enjoy listening to music on.

[gutr2]

Originally Posted by bcgood

Thanks I had fun with sculpting this audio clip. No, it isn't the Britcasti. Basically I combined some of the reverbs that come in Pro Tools 8 with a smidgen of Lexicon reverb.

Thanks for the HD 600 review, I think I'll probably pick up a pair if nothing else just to enjoy listening to music on.

VERY NICE! I found my pair new on ebay for a great price. Shop around, cause the prices do vary a lot.
Take care,
A

[gutr2]

Originally Posted by Audiop

Yes HD600 is thin in the low bass. HD650 is better but to thick in the upper bass/lower mid. Overall I feel HD600 is the better mix-tool though.

Any decent amp will do and do not really change the bass.

Best IME is to use HD650 with a slight EQ to tame the 60Hz-350hz bump or so. I'm planning to build a two channel head-amp with built in notch for HD650 and bass gain for HD600.

Most people agree on these listening impressions and my measurements supports this as well.

Check graphs in post #12.

Nearfield monitor most similar to HD-650s?


/Peter

Thanks for sharing Peter, that's really good to know.
That sounds like a great idea about the amp.
What amps do you recommend by the way? In audiophile forums you get even more opinions than slutz!
Cheers,
Andre